Pivotable sash window assemblies are well known in the art. Typically, these assemblies include a rotatable brake housing assembly actuated by rotation of a window sash pivot pin when the window sash is pivoted from its vertical position to a non-vertical position. The brake housing assembly locks the window sash relative to the window frame when the sash is pivoted, thereby preventing the sash from springing up due to the upward bias of the sash balance connected to the brake housing.
Typically, the window sashes, and associated balance and brake hardware, are pre-installed into a window frame to form the pivotable sash window assembly. The pivotable sash window assembly is then shipped for final installation into a house, building or other structure. During shipment and installation, vertical jambs of the window frame often bow, or deflect, away from the window sash. This bowing causes the pivot pins to dislocate from the brake assemblies allowing the window sashes to separate from the window frame. In the past, window manufacturers wrapped the window frame with metal bands or tape to prevent the frame from bowing during shipment. This, however, required additional materials and labor in preparing the sash window assembly for shipment.
U.S. Pat. No. 5,371,971, having the same assignee as the present invention, addresses this problem. U.S. Pat. No. 5,371,971 provides a simple, reliable sash balance brake and pivot pin assembly that secures a pivotable window sash in a window frame. The assembly prevents the vertical jambs of the frame from bowing out and distorting from the sash during shipment and installation, thus eliminating the need for wrapping the frames with metal bands or tape.
As disclosed in U.S. Pat. No. 5,371,971, a pair of sash balance brake and pivot pin assemblies are used for each window sash installed in the window frame. Specifically, the assembly includes a pivot pin extending outwardly from the window sash. The pivot pin has a collar extending radially outwardly around a circumference of the pivot pin. The assembly also includes a sash balance brake housing disposed within a track in the window frame. The brake housing is expandable and has an opening to rotatably support a rotor. The rotor has a first slot to receive the pivot pin. The rotor also has a second slot transversely disposed relative to the first slot and extending beyond the width of the first slot, thus defining an inner surface of the second slot. The pivot pin is inserted into the rotor from an opening in the top of the brake housing. The pivot pin is received by the first slot of the rotor while the collar on the pivot pin is simultaneously received by the second slot of the rotor. Once inserted, the collar engages the inner surface of the second slot preventing the pivot pin from moving laterally, or inwardly, relative to the brake housing. Because the window frame is attached to the track retaining the brake housing, the window frame is, therefore, prevented from bowing away from the window sash, thereby maintaining the window frame substantially square. While U.S. Pat. No. 5,371,971 utilized an expandable brake housing, the invention has also been utilized with brake housings that support a separate brake shoe.
The sash balance brake and pivot pin assembly of U.S. Pat. No. 5,371,971 has been very successful in preventing the window frame from bowing and distorting from the window sash. Window manufacturers have experienced a problem with the assemblies, however, when installing the window sash into the window frame, sometimes referred to as "racking the window sash." During installation, a portion of the rotor is occasionally cracked off the rotor.
To appreciate this problem, it is important to understand a typical installation procedure. When installing the window sash into the window frame, the brake housings retained in the tracks on each side of the window frame are horizontally aligned. A first pivot pin on one side of the sash is initially inserted into the rotor carried by the brake housing. The window sash is then necessarily positioned at an angle to properly align a second pivot pin with the rotor carried by the opposite brake housing. With the window sash positioned at this angle to allow insertion of the second pivot pin, the collar on the first pivot pin tends to engage and pry against the inner surface of the second slot of the rotor. This prying sometimes causes the portion of the rotor proximate the inner surface to crack off the rotor. The rotor must then be replaced in the brake housing, thus increasing material costs and installation time.
The present invention is provided to solve these and other problems.